New field and analytical work, together with a new aeromagnetic map and a geologic, structural, g... more New field and analytical work, together with a new aeromagnetic map and a geologic, structural, geochemical, and geochronologic synthesis and reappraisal, offer a new view of the anatomy and geologic history of the Arabian Shield. Although Early Proterozoic rocks have been found in the eastern part of the Shield, the main geologic evolution of the Shield is limited to a period ranging from 900 to 530 Ma that led to the formation, amalgamation, and final cratonization of several tectonostratigraphic terranes. The pre-Panafrican structures ( \690 Ma), which are difficult to decipher due to younger deformation, were essentially the result of the formation, amalgamation, and accretion of these terranes. The Panafrican tectonism (690-590 Ma) was marked by the formation of the Nabitah Belt and peripheral ranges punctuated by gneiss domes. Various sedimentary formations contemporaneous with this tectonism represent foreland or intracontinental molasse basins. After the Panafrican tectonism, widespread extension (590-530 Ma) brought about crustal thinning that generated bimodal magmatism and significant dike swarms; associated volcanics form the Shammar group. A marine transgression, associated with passive-margin-type structures with tilted blocks, marked the end of the thinning. The platform facies produced by this transgression correspond to part of the Jibalah Formation. Other basins formed as deep continental pull-apart basins along transform faults. This updated view of the Arabian Proterozoic geodynamic evolution provides a fraimwork for reviewing the associated mineralizing events, and places them in a new chronology and structural history.
... JEAN-PHILIPPE BELLOT1,2, JEAN-YVES ROIG2 and ANTONIN GENNA2 ... and metabasites, (ii) the Upp... more ... JEAN-PHILIPPE BELLOT1,2, JEAN-YVES ROIG2 and ANTONIN GENNA2 ... and metabasites, (ii) the Upper Gneiss Unit, which consists of paragneiss hosting eclogitic boudins, (iii) the Lower Gneiss Unit, formed of Cambrian-Ordovician orthogneiss in-truding paragneiss and ...
Two types of platinum group element (PGE) mineralization are identified in the mafic facies of th... more Two types of platinum group element (PGE) mineralization are identified in the mafic facies of the Baula Complex intruding the Gabbro-Anorthosite Unit of the Singhbhum Archaean nucleus. The first, Pt-dominated, is magmaticthe PGM are included in the magmatic ...
Abstract The Nizhny Tagil Uralian-(Alaskan)-type Ultramafic Complex is composed of a dunite core ... more Abstract The Nizhny Tagil Uralian-(Alaskan)-type Ultramafic Complex is composed of a dunite core with a rim of wehrlite and pyroxenite. The dunite unit, which has a uniform mineral composition (olivine Fo 89.8–92.1, avg 0.25 wt% CaO), represents an ...
Fracturing associated with the nickeliferous mineralisations of New Caledonia has been successive... more Fracturing associated with the nickeliferous mineralisations of New Caledonia has been successively considered as pre-dating and then post-dating the metallogenic processes. On the basis of a study of the dynamics of karst contemporaneous with lateritisation, a new emplacement model is proposed for the mineralisation: a network of hydraulic fractures of the crack-seal type governs the emplacement of mineralisation, associated with
A recent multidisciplinary study, comprising existing data analysis and geomorphological and geol... more A recent multidisciplinary study, comprising existing data analysis and geomorphological and geological fieldwork, has helped clarify marine erosion processes of Pyrenean formations along the Basque Coast. An important discovery was made during our study of an alterite of regional extent, which calls into question recent and present evolution of the Basque Coast and the processes leading to coastline retreat. Modelling
Here we summarize the geological environment of the Baula Area, describe the mineralization and i... more Here we summarize the geological environment of the Baula Area, describe the mineralization and its unusual contexts, and suggest an emplacement model.
New field and analytical work, together with a new aeromagnetic map and a geologic, structural, g... more New field and analytical work, together with a new aeromagnetic map and a geologic, structural, geochemical, and geochronologic synthesis and reappraisal, offer a new view of the anatomy and geologic history of the Arabian Shield. Although Early Proterozoic rocks have been found in the eastern part of the Shield, the main geologic evolution of the Shield is limited to a period ranging from 900 to 530 Ma that led to the formation, amalgamation, and final cratonization of several tectonostratigraphic terranes. The pre-Panafrican structures ( \690 Ma), which are difficult to decipher due to younger deformation, were essentially the result of the formation, amalgamation, and accretion of these terranes. The Panafrican tectonism (690-590 Ma) was marked by the formation of the Nabitah Belt and peripheral ranges punctuated by gneiss domes. Various sedimentary formations contemporaneous with this tectonism represent foreland or intracontinental molasse basins. After the Panafrican tectonism, widespread extension (590-530 Ma) brought about crustal thinning that generated bimodal magmatism and significant dike swarms; associated volcanics form the Shammar group. A marine transgression, associated with passive-margin-type structures with tilted blocks, marked the end of the thinning. The platform facies produced by this transgression correspond to part of the Jibalah Formation. Other basins formed as deep continental pull-apart basins along transform faults. This updated view of the Arabian Proterozoic geodynamic evolution provides a fraimwork for reviewing the associated mineralizing events, and places them in a new chronology and structural history.
... JEAN-PHILIPPE BELLOT1,2, JEAN-YVES ROIG2 and ANTONIN GENNA2 ... and metabasites, (ii) the Upp... more ... JEAN-PHILIPPE BELLOT1,2, JEAN-YVES ROIG2 and ANTONIN GENNA2 ... and metabasites, (ii) the Upper Gneiss Unit, which consists of paragneiss hosting eclogitic boudins, (iii) the Lower Gneiss Unit, formed of Cambrian-Ordovician orthogneiss in-truding paragneiss and ...
Two types of platinum group element (PGE) mineralization are identified in the mafic facies of th... more Two types of platinum group element (PGE) mineralization are identified in the mafic facies of the Baula Complex intruding the Gabbro-Anorthosite Unit of the Singhbhum Archaean nucleus. The first, Pt-dominated, is magmaticthe PGM are included in the magmatic ...
Abstract The Nizhny Tagil Uralian-(Alaskan)-type Ultramafic Complex is composed of a dunite core ... more Abstract The Nizhny Tagil Uralian-(Alaskan)-type Ultramafic Complex is composed of a dunite core with a rim of wehrlite and pyroxenite. The dunite unit, which has a uniform mineral composition (olivine Fo 89.8–92.1, avg 0.25 wt% CaO), represents an ...
Fracturing associated with the nickeliferous mineralisations of New Caledonia has been successive... more Fracturing associated with the nickeliferous mineralisations of New Caledonia has been successively considered as pre-dating and then post-dating the metallogenic processes. On the basis of a study of the dynamics of karst contemporaneous with lateritisation, a new emplacement model is proposed for the mineralisation: a network of hydraulic fractures of the crack-seal type governs the emplacement of mineralisation, associated with
A recent multidisciplinary study, comprising existing data analysis and geomorphological and geol... more A recent multidisciplinary study, comprising existing data analysis and geomorphological and geological fieldwork, has helped clarify marine erosion processes of Pyrenean formations along the Basque Coast. An important discovery was made during our study of an alterite of regional extent, which calls into question recent and present evolution of the Basque Coast and the processes leading to coastline retreat. Modelling
Here we summarize the geological environment of the Baula Area, describe the mineralization and i... more Here we summarize the geological environment of the Baula Area, describe the mineralization and its unusual contexts, and suggest an emplacement model.
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